Sheet stacking apparatus, sheet storage apparatus and image forming apparatus equipped with the same

ABSTRACT

A sheet stacking apparatus includes a sheet stacking unit having a stacking member, a contact member, a moving unit, and a regulating member. The contact member contacts an end portion of a sheet stacked on the stacking member. The moving unit moves the contact member from a standby position to a movement position to move the stacked sheet. The regulating member regulates, at a regulation position, a position of the stacked sheet from above, and moves from the regulation position by being pushed by the conveyed sheet. In a sheet width direction orthogonal to a direction in which the sheet is conveyed, the contact member and the regulating member are arranged at different positions, and in a thickness direction of the stacked sheet, an upper surface of the contact member located at the standby position is located above a lower surface of the regulating member located at the regulation position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet storage apparatus storing sheets, and to an image forming apparatus equipped with the sheet storage apparatus.

2. Description of the Related Art

Conventionally, in connection with an image forming apparatus such as a copying machine, there has been discussed a sheet post-processing apparatus which temporarily stores sheets in a sheet storage unit, and then discharges sheets in bundles or stapled sheet bundles. In Japanese Patent Application Laid-Open No. 2008-156089, in order to reliably discharge the sheet bundles by a discharge member configured to push out the sheet bundle, this pushing-out configuration has a claw shape, and on the upper surface of the claw, there is provided an eaves-shaped protrusion so that the sheet bundles do not slip from the discharge member.

However, in the case of the configuration discussed in Japanese Patent Application Laid-Open No. 2008-156089, it has been necessary for the sheets to be dropped to a pressing member by their own weight so that the sheets are reliably stacked between a stacking surface and the eaves-shaped portion of the pressing member. For this purpose, it has been necessary to increase the angle of a stacking portion to a nearly right angle (i.e., erect it), resulting in an increase in the height of the discharge sheet post-processing apparatus. On the other hand, recently, there has been a demand for a reduction in the size of image forming apparatuses. In particular, in the case of an image forming apparatus functioning as a multifunction peripheral, since a document reading device needs to be installed at a relatively lower position, there has been a strong demand for a reduction in the height of the image forming apparatus. Thus, there has been a requirement for the sheet post-processing apparatus to be also reduced in height.

SUMMARY OF THE INVENTION

Thus, the present invention is directed to a sheet storage apparatus capable of reliably discharging sheets while being reduced in height, and to an image forming apparatus equipped with the same.

According to an aspect of the present invention, a sheet stacking apparatus includes a sheet stacking unit having: a stacking member on which a sheet conveyed by a conveyance unit is stacked, a contact member configured to contact an end portion of the sheet stacked on the stacking member, a moving unit configured to move the contact member from a standby position to a movement position in order to move the sheet stacked on the stacking member, and a regulating member configured to regulate, at a regulation position, a position of the sheet stacked on the stacking member from above, and to move from the regulation position by being pushed by the sheet conveyed by the conveyance unit, wherein, in a sheet width direction orthogonal to a direction in which the conveyance unit conveys the sheet, the contact member and the regulating member are arranged at different positions, and in a thickness direction of the sheet stacked on the stacking member, an upper surface of the contact member located at the standby position is located above a lower surface of the regulating member located at the regulation position.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a configuration of a sheet storage unit according to a first exemplary embodiment.

FIGS. 2A and 2B are perspective views illustrating a configuration of the sheet storage unit according to the first exemplary embodiment.

FIG. 3 is a diagram illustrating a configuration of a discharge unit according to the first exemplary embodiment.

FIGS. 4A, 4B, and 4C are enlarged sectional views each illustrating a portion near a conveyance roller pair according to the first exemplary embodiment.

FIG. 5 is a diagram illustrating a configuration of an image forming apparatus according to the first exemplary embodiment.

FIG. 6 is an external perspective view illustrating the image forming apparatus according to the first exemplary embodiment.

FIG. 7 is a sectional view illustrating a configuration of a sheet storage unit according to a second exemplary embodiment.

FIG. 8 is a perspective view illustrating a configuration of the sheet storage unit according to the second exemplary embodiment.

FIGS. 9A, 9B, and 9C are enlarged sectional views each illustrating a portion near a conveyance roller pair according to the second exemplary embodiment.

FIG. 10 is a perspective view illustrating a discharge unit according to a third exemplary embodiment.

FIG. 11A, 11B, and 11C are enlarged sectional views each illustrating a portion near a conveyance roller pair according to the third exemplary embodiment.

FIGS. 12A, 12B, and 12C are enlarged sectional views each illustrating a portion near a conveyance roller pair according to a fourth exemplary embodiment.

FIGS. 13A, 13B, 13C, and 13D are enlarged sectional views each illustrating a portion near a conveyance roller pair according to a fifth exemplary embodiment.

FIGS. 14A and 14B are diagrams illustrating a modification.

FIG. 15 is a block diagram.

DESCRIPTION OF THE EMBODIMENTS

In the following, a first exemplary embodiment to which the present invention is applied will be described in detail with reference to the drawings. FIG. 5 is a diagram illustrating the configuration of an image forming apparatus 100 equipped with a sheet storage apparatus (stacking apparatus) 200 according to the first exemplary embodiment. As illustrated in FIG. 5, the image forming apparatus main body (hereinafter referred to as the apparatus main body) includes an image forming unit 101, a feeding unit 102 configured to feed sheets S to the image forming unit 101, a fixing unit 103, and a sheet discharge unit 104. Further, mounted to the apparatus main body 100 is the sheet storage apparatus 200 configured to temporarily store sheets S on which images have been formed.

The image forming unit 101 includes a photosensitive drum 111 configured to rotate clockwise in FIG. 5, an exposure device 113, and a charging roller 112, a developing device 114, and a transfer roller 115, which are arranged substantially in order in the rotational direction of the photosensitive drum 111. The image forming unit 101 forms toner images on the sheets S by an electrophotographic image forming process by using these processing devices.

Further, the feeding unit 102 feeding the sheets S includes a feeding cassette 105 storing sheets S on which image formation is to be performed, a feeding roller pair 107, a conveyance guide 109, and a regulation roller pair 110.

The fixing unit 103 includes a fixing roller 116, a pressing roller 117 held in contact with the fixing roller 116 from below, and a fixing/discharge roller pair 118, and is configured to fix the toner images formed on the sheets S by the image forming unit 101.

The sheet discharge unit 104 includes a first switching member 120, a conveyance roller pair 121, a discharge guide 122, a discharge roller pair 123, and a discharge/stacking portion 124 formed on the upper surface of the apparatus main body 100.

The switching member 120 is switched, by a central processing unit (CPU) 50 (FIG. 15), between a storage position indicated by the solid lines in FIG. 5 and a discharge position indicated by the broken lines in FIG. 5. At the storage position, the sheet S on which image formation is performed is caused to head for the sheet storage apparatus 200, whereas at the discharge position, the sheet S on which image formation is performed is discharged to the discharge/stacking portion 124.

FIG. 15 is a block diagram illustrating the configuration according to the first exemplary embodiment. As illustrated in FIG. 15, the CPU 50 is connected to a read-only memory (ROM) and a random-access memory (RAM). The CPU 50 uses the RAM as work memory, thereby executing a program stored in the ROM.

Next, the image forming operation of the apparatus main body 100 will be described. First, when image information is sent to the apparatus main body 100 from an external apparatus (personal computer (PC)) or a network such as a local-area network (LAN), the exposure device 113 emits laser light L according to the image information. This laser light L is emitted to the surface of the photosensitive drum 111, the surface of which is uniformly charged to a predetermined polarity and electrical potential by the charging roller 112, and the surface is thus exposed to the laser light L.

As a result, the electric charge is removed from the exposed portion of the surface of the photosensitive drum 111, and an electrostatic latent image is formed on the surface of the photosensitive drum 111. Then, toner is adhered to the photosensitive drum 111 by the developing device 114, whereby the electrostatic latent image is visualized as a toner image. The toner image on the photosensitive drum 111 is transferred to a sheet S at a transfer nip portion formed between the photosensitive drum 111 rotating clockwise and the transfer roller 115.

On the other hand, the sheets S supplied to the image forming unit 101 are separated and fed one by one from the feeding cassette 105 by the feeding roller pair 107, and are conveyed to the registration roller pair 110 along the conveyance guide 109. At this time, the registration roller pair 110 is at rest, so that the sheet S is temporarily stopped by the registration roller pair 110. Next, the sheet S temporarily stopped is conveyed to the transfer nip portion by the registration roller pair 110 which starts to rotate in synchronization with the formation of the toner image performed by the image forming unit 101.

The toner image on the photosensitive drum 111 is transferred to the sheet S by the transfer roller 115. After that, the sheet S to which the toner image has been transferred is conveyed to the fixing unit 103, and is nipped and conveyed by a fixing nip portion formed between the fixing roller 116 and the pressing roller 117. Then, the sheet S is heated and pressed, whereby the toner image is fixed to the surface of the sheet S.

When discharging and stacking the sheet S onto the discharge/stacking portion 124, the CPU 50 sets the first switching member 120 to the discharge position (the position indicated by the broken lines) where the sheet S is conveyed toward the discharge roller pair 123. As a result, the sheet S to which the toner image has been fixed is conveyed along the discharge guide 122 by the conveyance roller pair 121, and is discharged onto the discharge/stacking portion 124 by the discharge roller pair 123.

On the other hand, when conveying the sheet S to the sheet storage apparatus 200, the CPU 50 previously switches the first switching member 120 to the storage position indicated by the solid lines in FIG. 5. As a result, the sheet S is conveyed from the apparatus main body 100 toward the sheet storage apparatus 200 via a conveyance path 128.

The sheet storage apparatus 200 includes sheet storage units 201 through 203 stacked one upon another. Conveyance roller pairs (conveyance units) 204 through 206 convey the sheets S to the respective sheet storage units 201 through 203.

Further, the sheet storage units 201 through 203 respectively include leading edge regulating members 244 through 246 configured to regulate the downstream ends of the sheets S in the sheet conveyance direction, and discharge ports 234 through 236 for discharging the sheets S stored in the respective sheet storage units 201 through 203 to the exterior. The sheet storage units 201 through 203 further include regulating portions 241 through 243, respectively, which will be described below.

The conveyance destinations of the sheets S are switched by a second switching member 211 and a third switching member 212, and the sheets S are guided by conveyance guides 207 through 210, so that the sheets S are conveyed to the respective sheet storage units 201 through 203.

The CPU 50 switches each position of the second switching member 211 and the third switching member 212 between a position indicated by the solid lines and a position indicated by the broken lines in FIG. 5, by using an actuator 30 (not illustrated). For example, when conveying the sheet S to the sheet storage unit 201, the CPU 50 switches the first through third switching members 120, 211, and 212 to their respective positions indicated by the solid lines in FIG. 5, and retains them at these positions. As a result, the sheet S passes from the conveyance guide 128, and subsequently passes through the conveyance guides 207 and 208 in this order, and then, the sheet S is conveyed to the sheet storage unit 201.

Alternatively, when conveying the sheet S to the sheet storage unit 202, the CPU 50 switches only the third switching member 212 to the position indicated by the broken lines and retains it at that position. As a result, the sheet S passes through the conveyance guides 128, 207, and 209 in this order, and then, the sheet S is conveyed to the sheet storage unit 202.

Next, the configuration of the sheet storage apparatus 200 will be described in more detail. The sheet storage units 202 and 203 have similar configurations to that of the sheet storage unit 201. Thus, only the sheet storage unit 201 will be described, and the descriptions of the sheet storage units 202 and 203 will be omitted.

FIG. 1 is a sectional view illustrating the configuration of the sheet storage apparatus 200. The sheet storage unit 201 includes a stacking portion 231 where the sheets S conveyed by the conveyance roller pair 204 are stacked. The sheet storage unit 201 further includes a discharge unit 233 for discharging sheets S from the discharge port 234 so that a user can receive the leading edge portions of the sheets S stacked on the stacking portion 231. The discharge unit 233 has a stacking surface on which sheets S are stacked and two contact portions 233 a provided in the width direction of the sheets S and configured to contact the upstream edges of the sheets S in the conveyance direction. The width direction of the sheets S means a direction orthogonal to the direction in which the conveyance roller pair 204 conveys the sheets S.

The sheet storage unit 201 further includes the regulating portion 241 for pressing the sheets S (regulating the position of the sheets S) stacked on the stacking portion 231 from above. The regulating portion 241 is bent at a bending point, and includes a regulating surface substantially parallel to the stacking portion 231.

The sheet storage unit 201 further includes the leading edge regulating member 244 configured to regulate the leading edges of the sheets S stored in the sheet storage unit 201. The leading edge regulating member 244 is arranged such that the distance between the conveyance roller pair 204 and the sheet leading edge regulating member 244 is larger than the length of the sheets that are possibly stored. The leading edge regulating member 244 rotates around a rotation fulcrum 244 a and is reciprocated between a position indicated by the solid lines and a position indicated by the broken lines in FIG. 1 by the actuator 30 (not illustrated).

FIG. 3 is a top view illustrating the sheet storage unit 201 as seen from the perpendicular direction of the stacking portion 231. FIG. 3 illustrates only the components necessary for description such as the regulating portions 241, the discharge unit 233, and the contact portions 233 a, with the other components being omitted. For each contact portion 233 a, there is provided one regulating portion 241 on the outer side in the width direction of the sheets S (the direction orthogonal to the direction in which the contact portion 233 a moves) and in the vicinity thereof.

The discharge unit 233 can be moved in a discharge direction of the sheets S (the direction indicated by an arrow X in FIGS. 1 and 3) from a standby position to a discharge position (movement position) by a moving unit. Next, the moving unit for moving the discharge unit 233 between the standby position and the discharge position will be described with reference to FIG. 2.

FIGS. 2A and 2B are perspective views illustrating the upstream side portion of the sheet storage unit 201. FIGS. 2A and 2B each illustrate the conveyance roller pair 204, a part of the upstream side portion of the stacking portion 231, the discharge unit 233, the contact portions 233 a, and the regulating portions 241.

Referring to FIG. 2A, the discharge unit 233 is illustrated to be at the standby position where it does not hinder the conveyance and stacking of the sheets S in the sheet storage unit 201. On the other hand, referring to FIG. 2B, the discharge unit 233 is illustrated to be at the discharge position where it discharges the stored sheets S.

On one side in the width direction of the discharge unit 233, there is provided a rack 237. The rack 237 engages with a pinion 238, and the pinion 238 is connected with a motor (drive source) M1 (FIG. 15). The CPU 50 causes the motor M1 to perform normal and reverse rotation drive, whereby the pinion 238 is rotated by the drive force generated by the motor M1. As a result, the discharge unit 233 reciprocates between the standby position and the discharge position. When discharging the sheets S, the contact portions 233 a press the upstream side end portions of the sheets S to discharge the sheets S.

Next, the sheet discharge operational sequence and the positional relationship between the components will be described with reference to FIGS. 4A, 4B, 4C, and 6. FIGS. 4A, 4B, and 4C are enlarged views each illustrating a portion of the sheet storage unit 201 near the conveyance roller pair 204. FIG. 6 is an external perspective view illustrating the image forming apparatus 100.

First, the arrangement and configuration of the regulating portion 241 will be described. The regulating portion 241 has a flag shape so as to be pushed up by the leading edges of the sheets to be conveyed, and the rotation center (rotation fulcrum) 241 b thereof is arranged on the upstream side of the conveyance roller pair 204 in the conveyance direction. The above arrangement of the rotation center 241 b of the regulating portion 241 makes the contact angle between the sheets and the regulating portion 241 when the sheets S raise the regulating portion 241 small (shallow), thereby mitigating the damage to the leading edges of the sheets S. Further, the rotational path of a lowermost surface 241 a of the regulating portion 241 can be caused to approximate the sheet stacking direction (the vertical direction in FIGS. 4A, 4B, and 4C), so that, even when the trailing edges of the stacked sheets S are raised, it is possible to easily press them.

In FIG. 4A, the regulating portion 241 is located at a regulating position where it regulates the trailing edges of the sheets S such that they are not raised. At this time, the discharge unit 233 is in a state in which the sheets can be conveyed to the sheet storage unit 201, that is, at the standby position where it does not hinder the conveyance and stacking of the sheets S.

In this state, the regulating portion 241 has a regulation region (a section A-B in FIG. 4A) located below an uppermost surface 233 b of the contact portion 233 a in the thickness direction (stacking direction) of the sheets S. Further, the standby position of the contact portion 233 a is located within the regulation region in the conveyance direction of the sheets S. In other words, the contact portion 233 a and the regulating portion 241 overlap each other in the thickness direction of the sheets S (the vertical direction) (a section OL in FIG. 4A).

The conveyance roller pair 204 rotates in the direction indicated by an arrow in FIG. 4B, whereby the sheet S having passed a conveyance guide 261 is conveyed to the sheet storage unit 201. At this time, as illustrated in FIG. 4B, the regulating portion 241 is pressed by the sheets S, and retreats upwards as seen in the drawing using the rotation center 241 b as an axis. On the downstream side of the sheet storage unit 201, there is provided the leading edge regulating member 244 illustrated in FIG. 1. Thus, it is possible to prevent the sheets S conveyed by the conveyance roller pair 204 from protruding, and to prevent the already stored sheets S from being pushed out, so that the sheets S do not protrude from the discharge port 234.

When the user gives a discharge command through an operation display unit 292 (FIG. 6) provided on the apparatus main body, the discharge of the sheets S is started. When discharging the sheets S, the leading edge regulating member 244 is first opened by the actuator (not illustrated) to the position indicated by the broken lines in FIG. 1, thereby forming a conveyance path leading to the discharge port 234. After that, the discharge unit 233 moves from the standby position to the discharge position along the discharge direction.

In the present exemplary embodiment, even when the discharge unit 233 is at the discharge position, as illustrated in FIG. 4C, which is the position where the discharge unit 233 has completed the discharge of the sheets S, the contact portion 233 a is located within the regulation region of the regulating portion 241 illustrated in FIG. 4A.

When the discharge operation is completed, and the user receives the sheets discharged from the discharge port 234, a reception detection unit 70 (FIG. 15) recognizes that the user has received the sheets S, and the discharge portion 233 returns to the standby position illustrated in FIG. 4A. As a result, it is possible to accept the next sheet S.

According to the first exemplary embodiment described above, while reducing the height of the apparatus main body, the trailing edges of the sheets S can be prevented from slipping from the discharge unit 233 a during the discharge operation, causing defective discharge. As a result, the stored sheets S can be reliably discharged.

While in the first exemplary embodiment described above, the sheet storage apparatus 200 includes three sheet storage units 201 through 203, the configuration of the present invention is not limited thereto. For example, the sheet storage unit may be only one.

Further, while in the first exemplary embodiment described above, the sheet storage units 201 through 203 are arranged inside the image forming apparatus, the configuration of the present invention is not limited thereto. For example, the sheet storage units may be arranged outside the image forming apparatus.

Further, while in the first exemplary embodiment described above, the contact portions 233 a are moved by the rack 237 and the pinion 238, the configuration of the present invention is not limited thereto. For example, a member to be engaged with the contact portions 233 a may be provided on a belt configured to rotate by the drive force generated by a drive source.

Next, a second exemplary embodiment will be described with reference to FIGS. 7, 8, 9A, 9B, and 9C. In the following description of the second exemplary embodiment, the description of the configuration and operations that are common to the first exemplary embodiment will be omitted as appropriate. The second exemplary embodiment differs from the first exemplary embodiment in that there is provided a sheet guide member 371.

FIG. 7 is a sectional view illustrating a sheet storage unit 201 according to the second exemplary embodiment. The sheet guide member 371 has a guide configuration extending in a discharge direction X of the sheets S in FIG. 7.

FIG. 8 is a top view illustrating the sheet storage unit 201 as seen from the perpendicular direction of the stacking portion 231. FIG. 8 illustrates the regulating portions 241, the discharge unit 233, the contact portions 233 a, and the sheet guide members 371, which are necessary for the description. The descriptions of the other components are omitted. Each sheet guide member 371 is arranged between the contact portion 233 a and the regulating portion 241 in the width direction of the sheets S. Further, each sheet guide member 371 extends in the X-direction (the moving direction of the contact portion 233 a), and the sheet guide member 371 and the regulating portion 241 overlap each other in the X-direction as seen from the direction of FIG. 7 (the thickness direction of the sheets S).

Next, the sheet discharge operational sequence and the positional relationship between the components will be described with reference to FIGS. 9A, 9B, and 9C. The configurations and operations illustrated in FIGS. 9A and 9B are similar to those of the first exemplary embodiment, so the descriptions thereof will be omitted.

In the second exemplary embodiment, the moving amount of the contact portion 233 a in the X-direction can be made larger than that in the first exemplary embodiment. This is because, if the contact portion 233 a moves to the discharge position, the contact portion 233 a can overlap the sheet guide member 371, as illustrated in FIG. 9C. In this state, the uppermost surface 233 b of the contact portion 233 a is above a lowermost surface 371 a of the sheet guide member 371.

In other words, according to the second exemplary embodiment, the contact portion 233 a overlaps either the regulating portion 241 or the sheet guide member 371 without fail.

Thus, according to the second exemplary embodiment, in addition to the effects described in the first exemplary embodiment, defective discharge can be prevented even if the moving amount of the discharge unit 233 is increased.

Next, a third exemplary embodiment will be described with reference to FIGS. 10, 11A, 11B, and 11C. In the following description of the third exemplary embodiment, the description of the configuration and operations that are common to those of the first exemplary embodiment will be omitted as appropriate. The third exemplary embodiment differs from the first exemplary embodiment in that a discharge unit 433 includes an eaves-shaped portion 433 b.

FIG. 10 is a perspective view illustrating the upstream side portion of a sheet storage unit 201 according to the third exemplary embodiment. In FIG. 10, the sheet stacking portion 231 is omitted. FIGS. 11A, 11B, and 11C are enlarged views each illustrating a portion near the conveyance roller pair 204 according to the third exemplary embodiment.

In the third exemplary embodiment, the eaves-shaped portion 433 b is formed on the top surface of the discharge unit 433.

Next, the sheet discharge operational sequence and the positional relationship between the components will be described with reference to FIGS. 11A, 11B, and 11C. The configurations and operations illustrated in FIGS. 11A and 11B are similar to those of the first exemplary embodiment, so the descriptions thereof will be omitted.

In the third exemplary embodiment, while the discharge unit 433 is discharging the sheets S, a contact portion 433 a leaves the downstream side end (a portion B in FIG. 11A) of the regulating portion 241. At this time, the trailing edges of the sheets S have got under the eaves-shaped portion 433 b. Even when the discharge unit 433 is at the position (discharge position) where it has completed the discharge of the sheets S, as illustrated in FIG. 11C, a similar state continues to be maintained.

Thus, according to the third exemplary embodiment, in addition to the effects described in the first exemplary embodiment, the moving amount of the discharge unit 433 can be increased without increasing the number of components, so that defective discharge can be prevented.

Next, a fourth exemplary embodiment will be described with reference to FIGS. 12A, 12B, and 12C. In the following description of the fourth exemplary embodiment, the description of the configuration and operations that are common to those of the first exemplary embodiment will be omitted as appropriate. The fourth exemplary embodiment differs from the first exemplary embodiment in the configuration of a regulating portion 541.

FIGS. 12A, 12B, and 12C are enlarged views each illustrating a portion near the conveyance roller pair 204 according to the fourth exemplary embodiment.

In the fourth exemplary embodiment, a rotation center 541 b of the regulating portion 541 is located on the downstream side of the conveyance roller pair 204. The above arrangement of the rotation center 541 b causes the rotational path of a lowermost surface 541 a of the regulating portion 541 to approximate the thickness direction of the sheets S (the vertical direction in FIGS. 12A, 12B, and 12C), so that even when the trailing edges of the stacked sheets S are raised, it is possible to easily press them.

Next, the sheet discharge operational sequence and the positional relationship between the components will be described with reference to FIGS. 12A, 12B, and 12C. The configurations and operations illustrated in FIGS. 12A and 12B are similar to those of the first exemplary embodiment except that the regulating portion 541 rotates around the rotation center 541 b, so the descriptions thereof will be omitted.

Further, in the fourth exemplary embodiment, even when the discharge unit 233 is at the discharge position where it has completed the discharge of the sheets S as illustrated in FIG. 12C, the contact portion 233 a is located within the regulation region of the regulating portion 541 illustrated in FIG. 12A.

Thus, according to the fourth exemplary embodiment, in addition to the effects described in the first exemplary embodiment, the moving amount of the sheet discharge unit 233 can be increased without increasing the number of components, so that defective discharge can be prevented.

Next, a fifth exemplary embodiment will be described with reference to FIGS. 13A, 13B, 13C, and 13D. In the following description of the fifth exemplary embodiment, the description of the configuration and operations that are common to those of the first exemplary embodiment will be omitted as appropriate. The fifth exemplary embodiment differs from the first exemplary embodiment in the arrangement relationship of the regulating portion 241 and the contact portion 233 a in the conveyance direction (the moving direction of the contact portion 233 a).

FIGS. 13A, 13B, 13C, and 13D are enlarged views each illustrating a portion near the conveyance roller pair 204 according to the fifth exemplary embodiment.

In the fifth exemplary embodiment, when the contact portion 233 a is at the standby position, the regulating portion 241 and the contact portion 233 a do not overlap each other. As compared with the arrangement relationship in the first exemplary embodiment, in the fifth exemplary embodiment, the standby position of the contact portion 233 a is set to be on the upstream side in the conveyance direction.

As illustrated in FIG. 13C, during the movement of the contact portion 233 a from the standby position to the discharge position, and at a point in time when the contact portion 233 a comes into contact with the trailing edges of the sheets S, the regulating portion 241 and the contact portion 233 a overlap each other. In other words, the regulating portion 241 has a regulation region located below the uppermost surface 233 b of the contact portion 233 a in the thickness direction of the sheets S.

In addition, as illustrated in FIG. 13D, even when the discharge unit 233 is at the discharge position where it has completed the discharge of the sheets S, the contact portion 233 a and the regulating portion 241 continue to maintain the overlapped state described above.

Thus, according to the fifth exemplary embodiment, in addition to the effects described in the first exemplary embodiment, it is possible to provide a degree of freedom in connection with the standby position of the discharge unit 233.

The first through fifth exemplary embodiments described above may be combined with each other as appropriate. For example, while in the fifth exemplary embodiment, the contact portion 233 a overlaps the regulating portion 241 even at the discharge position, the configuration of the present invention is not limited thereto. It is also possible to combine the configuration of the fifth exemplary embodiment with the configuration of any of the first through fourth exemplary embodiments.

Further, as illustrated in FIGS. 14A and 14B as a modification, there may be provided an end portion regulating portion 731 being a stationary member below the conveyance roller pair 204 and on the downstream side of the standby position of the discharge unit 233. Due to the presence of the end portion regulating portion 731, it is possible to set the position where the lowermost surface 241 a of the regulating portion 241 and the contact portion 233 a overlap each other to be on the upstream side of the end portion regulating portion 731. Thus, when determining the arrangement (the overlapping position) of the contact portion 233 a and the regulating portion 241, there is no need to take into account the variation in the positions of the trailing edges of the sheets S when the sheets S are stored in the sheet storage unit 201.

According to an exemplary embodiment of the present invention, it is possible to provide a sheet storage unit capable of reliably discharging sheets while suppressing an increase in the height of the apparatus main body.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2013-184932 filed Sep. 6, 2013, which is hereby incorporated by reference herein in its entirety. 

What is claimed is:
 1. A sheet stacking apparatus comprising: a sheet stacking unit having: a stacking member on which a sheet conveyed by a conveyance unit is stacked, a contact member configured to contact an end portion of the sheet stacked on the stacking member, a moving unit configured to move the contact member from a standby position to a movement position in order to move the sheet stacked on the stacking member, and a regulating member configured to regulate, at a regulation position, a position of the sheet stacked on the stacking member from above, and to move from the regulation position by being pushed by the sheet conveyed by the conveyance unit, wherein, in a sheet width direction orthogonal to a direction in which the conveyance unit conveys the sheet, the contact member and the regulating member are arranged at different positions, and in a thickness direction of the sheet stacked on the stacking member, an upper surface of the contact member located at the standby position is located above a lower surface of the regulating member located at the regulation position.
 2. A sheet stacking apparatus comprising: a sheet stacking unit having: a stacking member on which a sheet conveyed by a conveyance unit is stacked, a contact member configured to contact an end portion of the sheet stacked on the stacking member, a moving unit configured to move the contact member from a standby position to a movement position in order to move the sheet stacked on the stacking member, and a regulating member configured to regulate, at a regulation position, a position of the sheet stacked on the stacking member from above, and to move from the regulation position by being pushed by the sheet conveyed by the conveyance unit, wherein, in a sheet width direction orthogonal to a direction in which the conveyance unit conveys the sheet, the contact member and the regulating member are arranged at different positions, and within a range in which the contact member contacts the sheet stacked on the stacking member when the contact member moves from the standby position to the movement position, an upper surface of the contact member is located above a lower surface of the regulating member located at the regulation position.
 3. The sheet stacking apparatus according to claim 1, wherein, the regulating member rotates around a rotation fulcrum on an upstream side of the conveyance unit in the direction in which the conveyance unit conveys the sheet.
 4. The sheet stacking apparatus according to claim 1, further comprising a sheet guide member on a downstream of the regulating member in a direction in which the contact member moves.
 5. The stacking apparatus according to claim 1, wherein the regulating member is bent at a bending point.
 6. The stacking apparatus according to claim 5, wherein the bending point is on an upstream side of the standby position of the contact member in a direction in which the contact member moves.
 7. The stacking apparatus according to claim 1, wherein the regulating member has a regulating surface substantially parallel to the stacking member.
 8. The stacking apparatus according to claim 1, wherein the conveyance unit includes a roller pair.
 9. The stacking apparatus according to claim 1, wherein the moving unit includes a drive source configured to generate drive force, a pinion configured to rotate by the drive force, and a rack provided on one side of the stacking member in the sheet width direction and configured to engage with the pinion.
 10. The stacking apparatus according to claim 1, further comprising an end portion regulating member fixed below the conveyance unit and configured to regulate a position of the end portion of the sheet.
 11. The stacking apparatus according to claim 1, wherein a plurality of sheet stacking units are stacked one upon another in the thickness direction of the sheet.
 12. An image forming apparatus comprising: an image forming unit configured form an image on a sheet; and a sheet stacking unit configured to stack the sheet on which the image has been formed by the image forming unit, the sheet stacking unit comprising: a stacking member on which a sheet conveyed by a conveyance unit is stacked, a contact member configured to contact an end portion of the sheet stacked on the stacking member, a moving unit configured to move the contact member from a standby position to a movement position in order to move the sheet stacked on the stacking member, and a regulating member configured to regulate, at a regulation position, a position of the sheet stacked on the stacking member from above, and to move from the regulation position by being pushed by the sheet conveyed by the conveyance unit, wherein, in a sheet width direction orthogonal to a direction in which the conveyance unit conveys the sheet, the contact member and the regulating member are arranged at different positions, and in a thickness direction of the sheet stacked on the stacking member, an upper surface of the contact member located at the standby position is located above a lower surface of the regulating member located at the regulation position. 